CN115726886A - Fan noise reduction device and aircraft engine comprising same - Google Patents
Fan noise reduction device and aircraft engine comprising same Download PDFInfo
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- CN115726886A CN115726886A CN202111003991.5A CN202111003991A CN115726886A CN 115726886 A CN115726886 A CN 115726886A CN 202111003991 A CN202111003991 A CN 202111003991A CN 115726886 A CN115726886 A CN 115726886A
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Abstract
The invention discloses a fan noise reduction device and an aircraft engine comprising the same, wherein the fan noise reduction device is arranged in a casing, airflow passing through the fan noise reduction device enters a fan, the fan noise reduction device comprises an inner surface flow channel and a noise reduction liner, and the inner surface flow channel is arranged on the inner surface of the casing; the noise reduction lining is arranged on the inner surface flow channel and comprises a resonant cavity, a back plate and a double-inclined-surface sound guide device, and the double-inclined-surface sound guide device is in a sawtooth type or a wave type. The double-inclined-plane sound guide device is a sawtooth type or a wave type, so that the low-frequency large-scale pulsating fluid structure can be accelerated to be broken into a high-frequency small-scale pulsating fluid structure which is easier to dissipate, and the backboard and resonant cavities with different heights integrally act to form an innovative noise reduction effect. The design of the sawtooth type double-bevel sound guide device changes the sound propagation path of noise entering through the small holes, and the heights of all resonant cavities are different, so that the broadband noise reduction effect is formed.
Description
Technical Field
The invention relates to a fan noise reduction device and an aircraft engine comprising the same.
Background
Data published by International Civil Aviation Organization (ICAO) in 2007 show that the number of passengers in the air in the same year reaches more than 20 hundred million people, civil aviation begins to enter the jet plane era, and the air transportation industry develops rapidly. With the rapid development of the air transportation industry, there are also social problems in that a very prominent end runs away from noise pollution around airports. With public concern over noise, governments and aviation organizations have set a series of standards that strictly define the noise level of an operating aircraft and specify that only noise-qualified aircraft will be able to obtain the pass issued by the country and allow for leaps and lands in their territories. Aircraft noise has become an important factor in evaluating aircraft performance and determining market competitiveness.
Aircraft noise mainly includes engine noise and airframe noise, wherein engine noise mainly includes jet noise, fan noise, turbine noise, and the like. After eighty years, along with the application of the pre-efficient silencing nacelle with the continuously improved bypass ratio of the aero-engine, the noise of the engine is effectively controlled. However, even with the high bypass ratio turbofan engine, the fan noise still occupies a significant position during the takeoff phase of the aircraft. Therefore, the fan noise is still one of the main noise sources of the modern turbofan engine with large bypass ratio, and how to reduce the fan noise of the engine is the important research problem of the noise reduction technology of the current engine.
When the speed of the fan blade tip is ultrasonic, extra shock wave noise can be generated, and the shock wave noise can be the main component of the fan noise when one end of the shock wave noise appears. With the increase of the mach number of the blade tip, the energy of shock wave noise is increased in a nonlinear way. The turbofan engine is generally designed by adopting ultrasonic blade tip, and the shock wave noise of the fan becomes a main factor influencing the noise of the whole engine and has obvious influence on seaworthiness noise and noise in a cabin.
At present, the main means for controlling shock wave noise comprise reasonable blade number arrangement, noise reduction lining laying and swept blade use. Wherein having the Blade Pass Frequency (BPF) below the cutoff frequency has become an important indicator of low noise fan design; on one hand, the sound liner increases the weight of the engine, and on the other hand, the sound absorption effect on low-modal shock wave noise is not ideal; experiments and mechanism researches on a large number of low-noise swept blades are carried out at home and abroad, but the low-noise swept blades are limited by aerodynamic performance, structural strength and the like, and the noise reduction effect is very limited, so that a new fan shock wave noise reduction technology needs to be researched urgently.
Disclosure of Invention
The invention aims to solve the technical problem that the noise reduction effect of an acoustic liner and a swept blade in the prior art is not ideal, and provides a fan noise reduction device and an aircraft engine comprising the same.
The invention solves the technical problems through the following technical scheme:
a fan noise reducer disposed in a housing, an airflow passing through the fan noise reducer entering a fan, the fan noise reducer comprising:
the inner surface flow channel is arranged on the inner surface of the casing;
the noise reduction lining is arranged on the inner surface flow channel and comprises a resonant cavity, a back plate and a double-inclined-surface sound guide device, and the double-inclined-surface sound guide device is in a sawtooth type or a wave type.
In the technical scheme, the double-inclined-plane sound guide device is of a sawtooth type or a wave type, so that the low-frequency large-scale pulsating fluid structure can be broken into a high-frequency small-scale pulsating fluid structure which is easier to dissipate, and the nonlinear attenuation process of the shock wave noise of the fan is accelerated. The double-inclined-plane sound guide device is a sawtooth type or wave type and can control shock waves, the shock waves on the surface of the double-inclined-plane sound guide device can be weakened when encountering the sawtooth type double-inclined-plane sound guide device, part of the shock waves can be locked in a sawtooth or wave structure, and the shock wave noise of the fan is stopped when being transmitted in a flow channel on the inner surface of the casing and cannot be transmitted forwards. Meanwhile, the back plate and the resonant cavities with different heights integrally act to form an innovative noise reduction effect.
Preferably, the inner surface flow channel is arranged between the blade leading edge of the fan and the air inlet throat of the fan, and the length of the inner surface flow channel is between 0.5m and 1 m.
In the technical scheme, the large-curvature inner surface flow channel has longer inner surface distance and area, the effective area of the noise reduction liner is obviously increased, the noise generated by the fan rotor is transmitted for a longer time in the front casing area, the action time with the noise liner is longer, and the noise reduction and absorption are facilitated. Meanwhile, the inner surface flow channel is arranged according to the large curvature, the double-inclined-plane sound guide devices on the inner surface flow channel are also arranged according to the large curvature, part of shock waves can be locked in the saw teeth under the action of the saw tooth type structure arranged according to the large curvature, and the shock wave noise of the fan is stopped when being transmitted in the inner surface flow channel of the large-curvature embedded type casing and cannot be transmitted forwards.
Preferably, the surface of the double-inclined-plane sound guide device is provided with small holes.
In the technical scheme, the small holes arranged on the surface of the double-inclined-plane sound guide device can increase air damping and enhance the noise attenuation capability.
Preferably, the small hole is communicated with the resonant cavity.
In the technical scheme, the small holes are communicated with the resonant cavity, so that sound waves can enter the resonant cavity through the small holes, and the attenuation and dissipation are performed. When the sound waves enter the resonant cavity through the small holes of the double-inclined-surface sound guide device, different sound wave propagation paths are formed, sound waves with different sound wave lengths are formed in the resonant cavity, the sound waves interfere with each other, and the sound energy dissipation and the noise elimination effect are improved.
Preferably, a plurality of the small holes are uniformly distributed on the double-inclined-plane sound guide device.
In the technical scheme, the small holes are uniformly distributed on the double-inclined-plane sound guide device, so that sound waves can enter the double-inclined-plane sound guide device through the small holes, the probability that the sound waves enter the resonant cavity is increased, and meanwhile, the small holes can also act together with the double-inclined-plane sound guide device, so that high-frequency sound waves cut by the double-inclined-plane sound guide device enter the resonant cavity.
Preferably, the double-inclined-plane sound guiding device is one acoustic wave long and/or the double-inclined-plane sound guiding device is 0.75 acoustic wave high.
In the technical scheme, the double-bevel sound guide device is one longer sound wave wavelength and 0.75 higher sound wave wavelength, so that noise enters the resonant cavity to perform up-and-down resonant motion, and the sound wave attenuation function is realized. The double-inclined-plane sound guide device can change the sound propagation path, and because the surface has large curvature, the height of each resonant cavity is different, and the sound propagation path can also be changed, so that the double-inclined-plane sound guide device and the resonant cavities can cooperatively change the sound propagation path. Meanwhile, the surface has large curvature, the height of each resonant cavity is different, the height of each resonant cavity is directly related to the noise frequency, the resonant cavities with different heights can eliminate the noise with different noise frequencies, and the broadband resonant cavity has broadband characteristics.
Preferably, the back plate is a rigid material.
In the technical scheme, the back plate is made of rigid materials, so that the structural strength of the back plate can be improved, and the service life of the noise reduction lining is prolonged.
Preferably, the surface of the double-inclined-plane sound guiding device is a smooth surface.
In the technical scheme, the surface of the double-inclined-plane sound guiding device is a smooth surface, so that the reflection efficiency of noise is greatly improved, and the mutual cancellation effect of the energy of sound waves is generated due to the overlapping of the amplitudes, so that the sound waves are well eliminated.
Preferably, the heights of the double-inclined-plane sound guiding devices are all the same.
In the technical scheme, the double-inclined-plane sound guide devices with the same height can uniformly reduce sound waves, the phenomenon that the sound waves of partial areas are concentrated and the partial areas cannot act is avoided, and the utilization efficiency of the fan noise reduction device is improved.
An aircraft engine comprises the fan noise reduction device.
Preferably, the aircraft engine comprises a fan noise reduction device, so that the breaking of the low-frequency large-scale pulsating fluid structure into the high-frequency small-scale pulsating fluid structure which is easier to dissipate can be accelerated, and the nonlinear attenuation process of the fan shock wave noise can be accelerated. The fan shock wave noise is stopped when propagating in the flow channel on the inner surface of the casing, and cannot be propagated forwards.
The positive progress effects of the invention are as follows:
the double-slope sound guide device is a sawtooth type or a wave type, so that the low-frequency large-scale pulsating fluid structure can be broken into a high-frequency small-scale pulsating fluid structure which is easy to dissipate, and the nonlinear attenuation process of the shock wave noise of the fan can be accelerated. The double-inclined-plane sound guide device is a sawtooth type or wave type and can control shock waves, the shock waves on the surface of the double-inclined-plane sound guide device can be weakened when encountering the sawtooth type double-inclined-plane sound guide device, part of the shock waves can be locked in a sawtooth or wave structure, and the shock wave noise of the fan is stopped when being transmitted in a flow channel on the inner surface of the casing and cannot be transmitted forwards. Meanwhile, the back plate and the resonant cavities with different heights integrally act to form an innovative noise reduction effect.
Drawings
Fig. 1 is a schematic structural diagram of a fan noise reduction device according to the present invention.
Fig. 2 is a schematic position diagram of the fan noise reduction device shown in fig. 1.
Fig. 3 is a side view of a double-chamfer sound guide of the fan noise reducer of fig. 1.
Fig. 4 is a top view of the double-inclined-plane sound guide of the fan noise reducer shown in fig. 1.
Fig. 5 is a schematic diagram of a frequency spectrum of shock wave noise of the fan noise reduction device shown in fig. 1.
Fig. 6 is a graphical illustration of the acoustic liner far field sound pressure curve of the fan noise reducer of fig. 1.
Description of the reference numerals
Outer duct flow guiding stator blade 2
Inner surface flow passage 3
Double-inclined-plane sound guide device 5
Back plate 6
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
As shown in fig. 1 and fig. 2, the present invention discloses a fan noise reduction device, which is disposed in a casing, and a fan rotor blade 1 and an outer duct flow stator blade 2 are disposed in the casing. The air flow passing through the fan noise reducer enters the fan. The fan noise reduction apparatus includes an inner surface flow passage 3 and a noise reduction liner. The inner surface flow passage 3 is provided on the inner surface of the casing. The noise reduction liner is arranged on the inner surface flow channel 3, and comprises a resonant cavity 4, a back plate 6 and a double-bevel sound guide device 5, wherein the double-bevel sound guide device 5 is in a sawtooth type or a wave type as shown in fig. 3 and 4.
The typical fan shock wave noise spectrum is schematically shown in fig. 5, and the double-inclined-surface sound guide device 5 is a sawtooth type or a wave type, so that the low-frequency large-scale pulsating fluid structure can be accelerated to be broken into a high-frequency small-scale pulsating fluid structure which is easier to dissipate. Modern high bypass ratio turbofan engine fan blade tips are typically supersonic and shock waves form near the blade tips. The double-inclined-plane sound guide device 5 can accelerate the nonlinear attenuation process of the fan shock wave noise. The double-bevel sound guide device 5 is in a sawtooth type or a wave type and can also control shock waves, and the shock waves on the surface of the shock waves can be weakened when meeting the sawtooth type double-bevel sound guide device 5. Part of the shock wave is locked in the sawtooth or wave structure, and the fan shock wave noise is stopped when propagating in the flow passage 3 on the inner surface of the casing and cannot be propagated forwards. Meanwhile, the back plate 6 and the resonant cavities 4 with different heights are integrally acted, so that an innovative noise reduction effect is formed.
As shown in fig. 1 and 2, the surface of the double-inclined-surface sound guiding device 5 is provided with small holes 7. The sawtooth type double-inclined-plane sound guide device 5 on the surface of the sound liner is a sawtooth type perforated plate, and the small holes 7 formed in the surface of the double-inclined-plane sound guide device 5 can increase air damping and enhance the noise attenuation capability. Meanwhile, the small holes 7 on the surface of the double-bevel sound guide device 5 are communicated with the resonant cavity 4, so that sound waves can enter the resonant cavity 4 through the small holes 7, and then attenuation and dissipation are performed. When the sound waves enter the resonant cavity 4 through the small holes 7 of the double-inclined-surface sound guide device 5, different sound wave propagation paths are formed, sound waves with different sound wave lengths are formed in the resonant cavity 4, and the sound waves interfere with each other, so that the sound energy dissipation and the noise elimination effect are increased.
As shown in fig. 1 and fig. 2, the plurality of small holes 7 are uniformly distributed on the double-inclined-plane sound guiding device 5, so that the sound waves can enter the double-inclined-plane sound guiding device 5 through the plurality of small holes 7, increasing the probability that the sound waves enter the resonant cavity 4, and meanwhile, the plurality of small holes 7 can also act together with the double-inclined-plane sound guiding device 5, so that the high-frequency sound waves divided by the double-inclined-plane sound guiding device 5 enter the resonant cavity 4.
As shown in fig. 1 and 2, the inner surface runner 3 is provided between the leading edge of the blade of the fan and the inlet throat of the fan, and the length of the inner surface runner 3 is between 0.5m and 1 m. The large-curvature inner surface flow channel 3 has longer inner surface distance and area, the effective area of the noise reduction liner is obviously increased, the noise generated by the fan rotor is spread in the front casing area for a longer time, the action time with the noise liner is longer, and the noise reduction and absorption are facilitated. Meanwhile, the inner surface runner 3 is arranged according to the large curvature, the double-inclined-plane sound guide devices 5 on the inner surface runner 3 are also arranged according to the large curvature, part of shock waves are locked in the saw teeth under the action of the saw tooth bulge arranged according to the large curvature, and the shock wave noise of the fan is stopped when being transmitted in the large-curvature embedded type casing inner surface runner 3 and cannot be transmitted forwards.
As shown in fig. 1 and 2, the double slant sound guiding device 5 is one acoustic wavelength longer or the double slant sound guiding device 5 is 0.75 acoustic wavelength higher. The noise enters the resonant cavity 4 to move up and down in a resonant mode, and the effect of attenuating the sound wave is achieved. The double-inclined-plane sound guide device 5 is one longer sound wave wavelength and the double-inclined-plane sound guide device 5 is 0.75 higher sound wave wavelength, and the two modes are arranged simultaneously, so that the effect of up-and-down resonant motion of noise entering the resonant cavity 4 is enhanced. The double-inclined-plane sound guiding device 5 changes the sound propagation path, and because the surface has a large curvature, the height of each resonant cavity 4 is different, and the sound propagation path is also changed, so that the double-inclined-plane sound guiding device 5 and the resonant cavity 4 can cooperatively change the sound propagation path. Meanwhile, the surface has large curvature, the height of each resonant cavity 4 is different, the height of each resonant cavity 4 is directly related to the noise frequency, and the resonant cavities 4 with different heights can eliminate the noise with different noise frequencies, so that the broadband resonant cavity has broadband characteristics. As shown in fig. 6, by comparing the sound attenuation effects of different designs, the far-field sound pressure curves of the 0.75-wavelength, 1-wavelength and 0.75-wavelength double-layer acoustic liner are compared, and as a result, the noise reduction effect of the 0.75-wavelength double-layer acoustic liner is found to be the best.
As shown in fig. 1 and 2, the back plate 6 is made of a rigid material, which can increase the structural strength of the back plate 6 and increase the service life of the noise reduction liner.
As shown in fig. 1 and 2, the double-inclined-surface sound guiding device 5 has a smooth surface. The smooth surface of the double-slope sound guiding device 5 greatly improves the reflection efficiency of noise, and the mutual cancellation effect of the energy of the sound waves occurs due to the overlapping of the amplitudes, so that the sound waves are well eliminated.
As shown in fig. 1 and 2, the height of the double-slope sound guiding device 5 is the same. The double-inclined-plane sound guide device 5 with the same height can uniformly reduce sound waves, the phenomena that sound waves in partial regions are concentrated and the partial regions cannot act are avoided, and the utilization efficiency of the fan noise reduction device is improved.
The invention also discloses an aircraft engine which comprises the fan noise reduction device. The aero-engine comprises the fan noise reduction device, the low-frequency large-scale pulsating fluid structure can be broken into the high-frequency small-scale pulsating fluid structure which is easy to dissipate, the nonlinear attenuation process of shock wave noise of the fan is accelerated, and therefore the aero-engine is better denoised.
While specific embodiments of the invention have been described above, it will be understood by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.
Claims (10)
1. A fan noise reducer, the fan noise reducer being disposed within a housing, an airflow passing through the fan noise reducer entering a fan, the fan noise reducer comprising:
the inner surface flow channel is arranged on the inner surface of the casing;
the noise reduction liner is arranged on the inner surface flow channel and comprises a resonant cavity, a back plate and a double-bevel sound guide device, and the double-bevel sound guide device is in a sawtooth type or a wave type.
2. The fan noise reduction device of claim 1, wherein the inner surface flow channel is disposed between a leading edge of a blade of the fan and an inlet throat of the fan, and the inner surface flow channel has a length of between 0.5m and 1 m.
3. The fan noise reduction apparatus of claim 1, wherein the surface of the double-inclined sound guide is provided with small holes.
4. The fan noise reduction apparatus of claim 3, wherein the small holes communicate with the resonance chamber.
5. The fan noise reduction apparatus of claim 3, wherein a plurality of the small holes are uniformly distributed on the double-inclined-plane sound guide apparatus.
6. The fan noise reduction apparatus of claim 1, wherein the dual slope sound guiding apparatus is one acoustic wavelength longer and/or the dual slope sound guiding apparatus is 0.75 acoustic wavelength higher.
7. The fan noise reduction device of claim 1, wherein the back plate is a rigid material.
8. The fan noise reduction apparatus of claim 1, wherein the surface of the dual-slope sound guiding device is a smooth surface.
9. The fan noise reduction apparatus of claim 1, wherein the dual-slope sound guiding means are all the same height.
10. An aircraft engine, characterized in that it comprises a fan noise reducing arrangement according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111003991.5A CN115726886A (en) | 2021-08-30 | 2021-08-30 | Fan noise reduction device and aircraft engine comprising same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111003991.5A CN115726886A (en) | 2021-08-30 | 2021-08-30 | Fan noise reduction device and aircraft engine comprising same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115726886A true CN115726886A (en) | 2023-03-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111003991.5A Pending CN115726886A (en) | 2021-08-30 | 2021-08-30 | Fan noise reduction device and aircraft engine comprising same |
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| Country | Link |
|---|---|
| CN (1) | CN115726886A (en) |
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2021
- 2021-08-30 CN CN202111003991.5A patent/CN115726886A/en active Pending
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